Methanol toxicity
, methanol blood level | differential = Infections, exposure to other s, 血清素综合症, 糖尿病酮症酸中毒 | prevention = | treatment = Antidote, 血液透析 | medication = Fomepizole, 乙醇 | prognosis = Good with early treatment | frequency = 1,700 cases per year (US) | deaths = }} 甲醇毒性（ ）是指因為身體內甲醇水平過量而引起的中毒病徵 。 Symptoms may include a , poor coordination, 呕吐, 腹痛, and a specific smell on the breath. 視力受損 may start as early as twelve hours after exposure. Long term outcomes may include blindness and 腎功能衰竭. Toxicity and death may occur even after drinking a small amount. Methanol poisoning most commonly occurs following the drinking of 风挡液. This may be accidental or done purposefully in an 自殺. Toxicity may also rarely occur through skin exposure or breathing in the fumes. When methanol is broken down by the body it results in 甲醛, 甲酸, and 甲酸酯 which cause much of the toxicity. The diagnosis may be suspected when there is 酸中毒 or an increased and confirmed by directly measuring blood levels. Other conditions that can produce similar symptoms include 感染, exposure to other s, 血清素综合症, and 糖尿病酮症酸中毒. Early treatment increases the chance of a good outcome. Treatment consists of stabilizing the person, followed by the use of an 解毒剂. The preferred antidote is , with 乙醇 used if this is not available. Hemodialysis may also be used in those where there is 器官 damage or a high degree of 酸中毒. Other treatments may include 碳酸氢钠, 叶酸, and 硫胺. s have occurred due to contamination of . This is more common in the 发展中国家. In 2013 more than 1700 cases occurred in the United States. Those affected are often adults and male. Outcomes may be good with early treatment. Toxicity to methanol has been described as early as 1856. Signs and symptoms The initial symptoms of methanol intoxication include , headache, dizziness, nausea, lack of coordination, and confusion. Sufficiently large doses cause unconsciousness and death. The initial symptoms of methanol exposure are usually less severe than the symptoms from the ingestion of a similar quantity of ethanol. Once the initial symptoms have passed, a second set of symptoms arises, from 10 to as many as 30 hours after the initial exposure, that may include blurring or complete loss of vision, 酸中毒, and hemorrhages, an uncommon but serious complication. These symptoms result from the accumulation of toxic levels of 甲酸酯 in the blood, and may progress to death by 呼吸衰竭. Physical examination may show 呼吸急促, and 眼科学 examination may show dilated 瞳孔s with of the optic disc and 视网膜l 水肿. Cause Methanol has a high toxicity in humans. As little as 10 mL of pure methanol when drunk is metabolized into 甲酸, which can cause permanent blindness by destruction of the 视神经. 15 mL is potentially fatal. Although the median lethal dose is typically 100 mL (3.4 fl oz) (i.e. 1–2 mL/kg body weight of pure methanol ). for methanol is 2 mg/kg/day.Methanol (CASRN 67-56-1) Ethanol is sometimes 變性乙醇 (adulterated), and made poisonous, by the addition of methanol. The result is known as methylated spirit, "meths" (British use) or "metho" (Australian slang). This is not to be confused with "meth", a common abbreviation for 甲基苯丙胺 and for 美沙酮 in Britain and the United States. Mechanism Methanol is 毒性 by two mechanisms. First, methanol (whether it enters the body by , 吸入, or through the skin) can be fatal due to its properties in the same manner as 酒精中毒. Second, in a process of , it is 代谢 to 甲酸 (which is present as the formate ion) via 甲醛 in a process initiated by the 酶 醇脫氫酶 in the 肝臟. Methanol is converted to formaldehyde via alcohol dehydrogenase (ADH) and formaldehyde is converted to formic acid (formate) via (ALDH). The conversion to formate via ALDH proceeds completely, with no detectable formaldehyde remaining. Formate is toxic because it inhibits mitochondrial 细胞色素c氧化酶, causing 缺氧 at the cellular level, and , among a variety of other metabolic disturbances. Treatment Methanol poisoning can be treated with , or if unavailable, ethanol. Both drugs act to reduce the action of 醇脫氫酶 on methanol by means of 競爭性抑制劑. 乙醇, the active ingredient in alcoholic beverages, acts as a competitive inhibitor by more effectively binding and saturating the alcohol dehydrogenase enzyme in the liver, thus blocking the binding of methanol. Methanol is excreted by the 腎s without being converted into the very toxic metabolites formaldehyde and formic acid. Alcohol dehydrogenase instead enzymatically converts ethanol to 乙醛, a much less toxic organic molecule.Voet, Donald, Judith G. Voet, and Charlotte W. Pratt. Fundamentals of Biochemistry: Life at the Molecular Level. 5th ed. Hoboken, NJ: Wiley, 2008. Print Additional treatment may include 碳酸氢钠 for metabolic acidosis, and 血液透析 or to remove methanol and formate from the blood. or 叶酸 is also administered to enhance the metabolism of formate. History There are cases of methanol resistance, such as that of , whom someone tried and failed to poison by methanol in the early 1930s.Blum, Deborah (2011). The Poisoner's Handbook. Penguin Books. p. 231. . In December 2016, from methanol poisoning after ingesting a counterfeit body lotion that was primarily methanol rather than ethanol as labeled. The body lotion, prior to the event, had been used as a cheap substitute for vodka by the impoverished people in the region despite warnings on the lotion's bottles that it was not safe for drinking and long-standing problems with alcohol poisoning across the country. 參考文獻 外部連結 | ICD9 = | ICDO = | OMIM = | DiseasesDB = | MedlinePlus = | eMedicineSubj = | eMedicineTopic = | MeSH = | GeneReviewsNBK = | GeneReviewsName = | Orphanet = }} Category:毒理学 Category:RTT Category:RTTEM